Fluid samples taken from the human or animal body are required for a wide variety of diagnostic and other biochemical tests, including the measurement of immunological reactions (immunoassays). There is accordingly a need for a device which can be conveniently used for collecting and storing such samples. Since the samples may pose a microbiological contamination or heath risk, the device used for their collection should not allow unintended release of the samples during storage, transportation or manipulation. The sample collection device is preferably disposable.
A known sample collection device for whole blood comprises an open-ended linear capillary tube formed of glass. The tube typically has an internal diameter of between one and two millimeters. To prevent clotting of the collected blood, the internal surface of the tube may be coated with a suitable anticoagulant such as heparin, which may also serve to reduce the contact angle between the sample and the side of the tube.
In use of the known device, the skin on the tip of a patient's finger is pierced by a lancet or other sharp piercing member. The blood so elicited is drawn into the linear tube by capillary action. The volume of the blood sample and the rate at which it is collected may be maximized by holding the tube with a generally horizontal orientation. The volume of the sample collected in this way is usually of the order of 25-100 μL.
A problem associated with the blood sample collection device described above relates to the transportation and handling of the sample subsequent to its collection. In particular, when the orientation of the linear tube is changed, there is a risk that gravitational forces acting on the sample may exceed the intermolecular forces which maintain the sample in the tube, leading to the unintended release of a portion of the sample and the associated microbiological contamination or heath risk. This problem may be exacerbated when the linear tube is also subjected to accelerations caused by sudden movements or decelerations caused by small knocks, etc.
To prevent the unintended release of the sample, it is known to stopper one or both ends of the linear capillary tube, for example using silicone bungs or sealant. However, there remains a risk that a portion of the sample may be accidentally released before the ends of the tube have been sealed or after the seal has been removed for subsequent processing.
There are many challenges in designing a sample collection device to be use in conjunction with further sample manipulation such as diagnostic testing. These include: minimizing contamination due to premature dispense or leakage from the sample collection device; enabling collection directly from a patient (i.e., finger stick) as well as from peripheral sample collection devices such as collection tubes or syringes; insufficient transfer of the sample to the manipulation device; ensuring collection volume is sufficient for the sample manipulation process; sample evaporation; minimizing the ability to re-open the sample collection device to avoid contamination; or other sources of inaccuracies in the sample manipulation process. Thus, there is a need in the art for an improved sample collection device for that overcomes the problems of the known art described above. In particular there is a need in the art for an improved sample collection device, which fluids are generally aqueous, and particularly such a device for which the risk of accidentally release of a portion of the sample subsequent to its collection may be reduced.